Confinement Effect in Layered Double Hydroxide Nanoreactor: Improved Optical Sensing Selectivity

Confinement effect in the layered double hydroxide (LDH) nanoreactors can control the reaction rate and disperse the fluorescence guest, which are promising to be introduced in optical sensing systems. In this work, an optical sensor has been fabricated 'by combining the confinement effect from the LDH nanoreactors with advantageous sensing performances of graphene quantum dots (GQDs). The mechanism indicated the LDHs with two dimensional (2D) confined space provided a stable microenvironment and acted as the disperse matrix to control the distribution of intercalated GQDs. Such a confinement effect may decrease the diffusion rate of hydroxyl radicals (*OH), and thus *OH with the short lifetime (10(-9) s) is annihilated during the diffusing process into the LDH interlayer galleries. As a result, the inherently existing interference from *OH for detection of NO2 was eliminated. Furthermore, a rapid and portable fluorescent paper sensor coated with the as-prepared GQD-LDHs for visual detection of NO2 gas was successfully developed. Our work provides a feasible method to remarkably improve the selectivity by virtue of confinement effect.